Adding more game dev tools.

Adding entries for Texture Packer, ShoeBox and Tiled Map Editor.
Removing Blender entry since it's not really relevant for 2D game development, organizing tools by category
Removing unnecessary intro text.
Update 04-game-development-tools.html.md
Update 04-game-development-tools.html.md
Update 04-game-development-tools.html.md
Merge pull request #110 from gamedevsam/master

Adding more game dev tools.